Cimetidine is a histamine H.sub.2 -antagonist which has been shown to be useful in the treatment of duodenal, gastric, recurrent and stomal ulceration. It is also employed in the management of patients who are at high risk from hemorrhage of the upper gastrointestinal tract.
Cimetidine is known to be one of many medicaments to have a pronounced bitter taste. This is not usually a problem when the dosage form employed is a capsule or a tablet designed to be swallowed, thereafter to disintegrate upon reaching the stomach. However, such dosage forms can be impractical when it is desired to administer a large amount of active ingredient, or to co-administer a relatively bulky second active ingredient such as an antacid or alginate. Moreover, many individuals have difficulty in swallowing a solid dosage form
A conventional approach to administering relatively large amounts of active ingredient in a solid dosage form is by means of a chewable tablet, i.e., a tablet which disintegrates in the mouth upon being chewed. Such a tablet also circumvents the problem of a solid dosage being difficult to swallow.
It will be appreciated that a major requirement of such a dosage form is that it must be palatable, since an unpalatable formulation increases the risk of a patient neglecting to take the tablet. Such non-compliance with the dosing regimen will in turn delay or prevent the patient's recovery from the condition under treatment.
A further requirement of such a composition is that once the disintegrated tablet reaches the stomach, the individual particles should release the active ingredient rapidly and completely in order to ensure that substantially all of the active ingredient is absorbed; that is to say the formulation should be readily bioavailable.
In the case of cimetidine, because of its bitterness and solubility characteristics, the provision of such a dosage form represents a considerable problem.
Several solutions to the problem of taste masking pharmaceutical compositions have been attempted. For example, cimetidine granules have been coated with various compositions such as ethylcellulose and polyvinyl and acrylic polymers. One such proposal is disclosed in U.S. Pat. No. 4,800,087 wherein a polymer mixture coating is employed. The mixture comprises a high temperature film forming copolymer of polymethyacrylic acid ester and acrylic acid ester and a low temperature film forming copolymers consisting of methacrylic acid ester and styrene acrylate. U.S. Pat. No. 4,892,740 discloses pharmaceutical preparations having improved flavouring characteristics obtained by the drug being coated by a polymeric substance which is soluble in gastic juice.